Natural N-terminal fragments of brain abundant myristoylated protein BASP1.

BASP1 (also known as CAP-23 and NAP-22) is a novel myristoylated calmodulin-binding protein, abundant in nerve terminals. It is considered as a signal protein participating in neurite outgrowth and synaptic plasticity. BASP1 is also present in significant amounts in kidney, testis, and lymphoid tissues.

RasGAP-associated endoribonuclease G3Bp: selective RNA degradation and phosphorylation-dependent localization.

Mitogen activation of mRNA decay pathways likely involves specific endoribonucleases, such as G3BP, a phosphorylation-dependent endoribonuclease that associates with RasGAP in dividing but not quiescent cells. G3BP exclusively cleaves between cytosine and adenine (CA) after a specific interaction with RNA through the carboxyl-terminal RRM-type RNA binding motif. Accordingly, G3BP is tightly associated with a subset of poly(A)(+) mRNAs containing its high-affinity binding sequence, such as the c-myc mRNA in mouse embryonic fibroblasts.

Phosphorylation of AZT-resistant human immunodeficiency virus type 1 reverse transcriptase by casein kinase II in vitro: effects on inhibitor sensitivity.

Casein kinase II (CKII) phosphorylates wild-type (WT) recombinant reverse transcriptase (RT) mainly in the p66 subunit in vitro. Phosphorylation of T215F RT and D67N/K70R/T215F/K219Q RT (AZT-resistant RT) in vitro increases discrimination against AZTTP 2. 5- and 3.

Detection of nucleotide- and F-actin-induced movements in the switch II helix of the skeletal myosin using its differential oxidative cleavage mediated by an iron-EDTA complex disulfide-linked to the strong actin binding site.

We have synthesized the mixed disulfide, S-(2-nitro-5-thiobenzoic acid) cysteaminyl-EDTA, using a rapid procedure and water-soluble chemistry. Its disulfide-thiol exchange reaction with rabbit myosin subfragment-1 (S-1), analyzed by spectrophotometry, ATPase assays, and peptide mapping, led to the incorporation of the cysteaminyl-EDTA group into only Cys 540 on the heavy chain and into the unique cysteine on the alkali light chains. The former thiol, residing in the strong actin binding site, reacted at a much faster rate with a concomitant 3-fold decrease in the V(max) for acto-S-1 ATPase but without change in the essential enzymatic functions of S-1.

A novel phosphorylation-dependent RNase activity of GAP-SH3 binding protein: a potential link between signal transduction and RNA stability.

A potential p120 GTPase-activating protein (RasGAP) effector, G3BP (RasGAP Src homology 3 [SH3] binding protein), was previously identified based on its ability to bind the SH3 domain of RasGAP. Here we show that G3BP colocalizes and physically interacts with RasGAP at the plasma membrane of serum-stimulated but not quiescent Chinese hamster lung fibroblasts. In quiescent cells, G3BP was hyperphosphorylated on serine residues, and this modification was essential for its activity.